JP3194949B2 - Acceleration detector - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to an acceleration detecting device of the type described in the preamble of claim 1.

In known detectors of this type, a permanent magnet is fixed as a vibrating mass to a flexure spring, which is operatively connected to a Hall element in order to generate a measuring signal. The Hall element is fixed to a hybrid arranged on a substrate of the acceleration detection device. The flexure spring is formed vertically with respect to the hybrid and has a longitudinal edge which extends obliquely, so that the pivoting of the flexure spring is prevented. However, due to this arrangement of the flexure springs and the configuration of the flexure springs, the acceleration detection device is made relatively high. In addition, if the acceleration detector falls, the flexure spring is easily bent or plastically deformed, which leads to errors in the measured values or the acceleration detector can no longer be used.

Advantages of the invention The advantage of the acceleration detection device according to the invention as set forth in the characterizing part of claim 1 lies in the fact that the structural height is very small, ie the structural volume is very small. The flexure spring with the oscillating mass is protected and is arranged in the recess of the plate. This provides fall safety on concrete at least from a height of one meter. The plate itself and the hybrids located on the plate are used as overload protection.
In addition, such an arrangement encloses the bending spring and the sensing magnet, so that contamination of the measuring device is prevented. The resonance frequency of the flexure spring can be influenced in a simple manner by choosing the material of the flexure spring. By selecting a material springback for the flexure spring, the flexure spring no longer plastically deforms in the sensing direction and the buckling direction. Due to the geometrically best designed stop for the oscillating mass, a substantially straight line is obtained as the measured signal course.
At the same time, the sensing magnet forms an oscillating mass, so that the oscillating mass is kept as small as possible, whereby a relatively large magnetic induction action is obtained based on the choice of permanent magnet. The rear side of the hybrid is connected to the vehicle ground based on the connection with the stopper plate and the connection with the substrate of the casing. This results in relatively low EMV sensitivity (EMV = electromagnetic compatibility). The number of components used is relatively small. Furthermore, the detection device can be manufactured in a small number of assembly and joining steps. Assembly of the detection device can take place almost completely automatically. After mounting the plug-in casing, the hybrid is balanced in a simple manner, in which case the casing itself has not yet been pressed. By using bonding technology as the connection type between the hybrid and the plug, this manufacturing step can be automated and can be performed reliably with a very low waste rate.

Since the permanent magnets are attracted to each other, it is sufficient to use a simple adhesive. Adhesives are inherently necessary only to prevent the permanent magnets from moving in the event of an impact. A high mounting accuracy in the vehicle can be obtained with the board used having the connection flange. Due to the simple symmetrical construction of the acceleration detector and the solid and stable measuring element, good temperature characteristics of the detector are obtained.
The inner space of the casing used is so large that different hybrids can be used at any one time, in particular hybrids with IC frames can also be used. When a hybrid having a large loss output and a hybrid having a high generated heat are used, this heat can be guided toward the vehicle chassis via the substrate. The detection device can be manufactured very cheaply. The measuring element fixed to the plug-in housing is only pushed into the housing, in which case the housing and the plug-in housing are locked together.

Advantageous configurations of the acceleration detecting device according to the present invention according to claim 1 are obtained by the configuration of the present invention described in the other claims.

 The invention will now be described with reference to the illustrated embodiment.

In this case, FIG. 1 is a view showing the pre-assembly structure inserted into the casing of the acceleration detecting device, and FIG. 2 is a view showing the pre-assembly structure.
FIG. 3 is a view showing a plate having a welded bending spring and a vibrating mass body, FIG. 4 is a view showing a substrate, and FIG. 5 is a longitudinal section of the acceleration detecting device of FIG. FIG. 6 is a view showing the inside of the casing, and FIGS. 7 to 10 are views showing a modified embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a housing 10 of an acceleration detecting device 11 with reference numeral 10 which is provided with an electrical connection plug (not shown in FIG. 1) which is snap-fitted in the housing 10. It has a plug-in casing 12 provided. The structure of the acceleration detecting device 11 is clear from FIG. The stopper plate 13 is fixed to the insertion casing 12 via a number of flat-head rivets 14. As is apparent from FIG. 3, the stopper plate 13 has a notch 15 having a substantially T-shaped cross section, in which a substantially rectangular flexible spring 17 and a vibrating mass 18 are provided. A measuring member 16 is arranged. The notch 15 allows the flexibility of the flexure spring 17 necessary for the desired measurement range, while the stopper plate 13 simultaneously serves as a stopper for the measurement member 16 and thus prevents the flexure spring 17 from overloading. It is formed in such a size as to be used as. In the range of the bending spring 17, the notch 15 allows the movability of the bending spring 17 within a desired measurement range. Let me know. The flexure spring 17 and the vibrating mass 18 must not protrude from the upper or lower surface of the stopper plate 13 to protect against mechanical damage. The bending spring 17 is formed from a material tonbag.

The bending spring 17 is fixed at one end to the stopper plate 13 by laser welding. The oscillating mass 18 is formed by two permanent magnets 20, 21 whose polarity is oriented perpendicular to the direction of movement of the flexure spring 17. Further, since the polarities of the two permanent magnets 20 and 21 are opposite, the permanent magnets 20 and 21 disposed on both sides of the bending spring 17 are attracted to each other. Permanent magnets 20 and 21 are additionally bonded, and in this case
A simple and inexpensive adhesive is sufficient to prevent mutual movement between 20,21.

As is clear from FIG. 2, a hybrid 25 is provided on the stopper plate 13, and a thick film resistor 27 and an electronic component 28, for example, an electric evaluation circuit are provided on a support 26 of the hybrid. A transistor, a resistor and the like are arranged. The electronic components 28 are connected to one another via thick conductor tracks or bonding wires. Furthermore, a Hall element 30 is provided on the hybrid support 26 and must be arranged as centrally as possible above the line of contact of the two permanent magnets 20,21. Plug-in casing
Hybrid 25 by stopper member 32 formed in 12
The support 26 is adjusted on the stopper plate 13. The electronic component 28 of the hybrid 25 is a bonding wire
33 is connected to the plug of the plug-in casing 12.

The stopper plate 13 is in contact with a guide member 35 evident from FIG. The casing 10 is mounted on a substrate 36 provided with two flange-shaped attachment portions 37 or is injection-molded. The substrate 36 has a cutout 38 on each side in the area of the flange-shaped addition part 37, into which a casing addition part 39 protrudes for fixing.

As is clear from FIG. 5, the stopper plate 13 is mounted on the substrate 36. Substrate 36 itself is formed from copper or another non-magnetic, conductive material. Therefore, the substrate closes the lower surface of the notch 15 of the stopper plate 13 and thus closes the measuring member.
It is also operatively connected to the 16 permanent magnets 20,21. Thereby, a combined function of the permanent magnets 20, 21 is obtained. The permanent magnets 20, 21 act as oscillating masses 18 of the flexure spring 17, and the permanent magnets cooperate with the substrate 36 to damp the vibration of the flexure spring 17. When the permanent magnets 20, 21 move, an eddy current is generated in the substrate 36, and this eddy current acts against the movement of the bending spring 17 and thus attenuates this movement.

The acceleration detection device 11 is arranged, for example, in a direction perpendicular to the traveling direction of the vehicle. Flex spring 17 and permanent magnets 20 and 2
The inertial mass as 1 deviates in proportion to the acceleration acting on the bending spring 17 in the vertical direction. Furthermore, such deviations are defined by the spring constant of the flexure spring 17, ie the spring shape and material, and the inertial mass. The measuring signal is generated in the region of the Hall element 30 by the movement of the permanent magnets 20, 21, ie by the movement of the magnetic field produced by the permanent magnets. The change in the magnetic field induces a voltage in the Hall element 30 as is well known, and this voltage is
Is evaluated by an electronic evaluation circuit. A slight displacement of the flexure spring 17 already changes the magnetic field in the region of the Hall element 30. At the same time, the vibration of the bending spring 17 is attenuated based on the eddy current generated in the substrate surface due to the movement of the permanent magnets 20,21. Due to the eddy current induced based on the vibration, the vibration energy of the bending spring 17 disappears. Proper deflection of the flexure spring / magnetic circuit system provides the desired damping effect in each case.

Based on the configuration of the acceleration detecting device 11, the acceleration detecting device 11 is manufactured particularly simply and at low cost. For this purpose, the bending spring 17 is inserted into the notch 15 of the stopper plate 13 together with the permanent magnets 20 and 21 adhered to one end, and one end of the bending spring 17 is fixed to the stopper plate 13 by laser welding. The stopper plate 13 is now fixed to the insert casing 12 via a flat-head rivet 14. The hybrid 25 previously manufactured in the next manufacturing step is adhered on the stopper plate 13 together with the thick film resistor 27 and the electronic component 28 arranged on the support 26. In this case, the stopper strip 32 of the insert casing 12 is used to center the hybrid 25 on the stopper plate 13. The longitudinal axis of the hybrid can be shifted with a simple additional adjusting device applied to the stopper plate 13 for a short time, so that the Hall element 30 is located exactly above the contact line of the two permanent magnets 20, 21 . Such centering is necessary to obtain an accurate and best reproducible measurement signal. The adjusting device is then removed again. The adhesive fixing the hybrid 25 on the stopper plate 13 can now be cured. The hybrid 25 is electrically connected to a plug of the plug-in casing 12 using a bonding wire 33. This results in a prefabricated, easy-to-handle pre-assembled structure, as shown in FIG.

The casing 10 is formed from an injection molding material and
Injection molded on top. Thus, a second pre-assembly structure comprising the substrate 36 and the casing 10 which are fixedly connected to each other is obtained. The pre-assembled structures are pushed together, in which case the plug-in casing 12 is snap-fit into a recess 42 of the casing 10 by a locking projection 41.

Hybrid before assembling both pre-assembled structures
25 are electronically balanced and checked.

In the variant shown in FIGS. 7 to 10, the connecting plate 13a is approximately centered between the welding point of the flexure spring 17 and the permanent magnets 20, 21 used as oscillating masses, the weight of the connecting plate 13a being Notch 4 to reduce as much as possible
It has 4,45. Furthermore, the substrate is composed of multiple parts and is composed of a copper plate 36a and a thin strip 37a. Copper plate 36a
Has substantially the same shape as the connection plate 13a. In this case, the thin plate strip 37a performs the function of the additional portion 37 provided in the case of another embodiment. The copper plate 36a contacts the lower surface of the connection plate 13a and has the same function as described above for the substrate 36. The connection plate 13a is mounted on the copper plate 36a in the case of assembling, and as described above, the hybrid 2
The first pre-assembly structure is obtained because it is secured in the bayonet casing 12 using a number of flat head rivets 14 together with 5. When the casing 10 is injection-molded, the thin strips 37a are already fixed to the casing together. This also results in a second pre-assembly structure.
The two pre-assembly structures are pushed into each other and the acceleration detection device is fixed to the vehicle via the strip 37a.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Willich, Rainer W-7146 Tamverbacher Wech 21 (56) References JP-A-2-151770 (JP, A) JP-A-2-249975 (JP) JP-A-1-145573 (JP, A) JP-A-63-1975 (JP, A) JP-A-3-71060 (JP, A) JP-A-1-124564 (JP, U) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01P 15/08 G01P 15/105-15/11

Claims (9)

(57) [Claims] 1. An acceleration detecting device (11), comprising a flexible spring (17) fixed on one side provided in a casing (10), at least one free end of which is provided on the free end of the flexible spring. In the type in which the two detecting members (20, 21) are fixed and the detecting members are operatively connected to the Hall element (30), the bending spring (17) is provided together with the detecting members (20, 21) with the plate. A hybrid (25) having a Hall element (30) is provided in the notch (15) of (13), and the size of the notch is overloaded. An acceleration detecting device characterized by being designed to provide a protective action. 2. The acceleration detecting device according to claim 1, wherein an end of the bending spring opposite to the detection member is welded to the plate. 3. The acceleration detecting device according to claim 1, wherein the bending spring has a substantially rectangular shape. 4. The size of the notch (15) is equal to that of the bending spring (17).
The acceleration detection device according to any one of claims 1 to 3, wherein the acceleration detection device is adapted to a measurement range of: 5. The acceleration according to claim 1, wherein the plate is fixed to the plug-in casing of the casing via a number of flat-head rivets. Detection device. 6. A substrate (36) disposed on a casing (10).
Has a fixing flange (37), and the substrate (36)
The acceleration detection device according to any one of claims 1 to 5, wherein at least the detection member (20, 21) is in contact with the plate side opposite to the hybrid (25). 7. The acceleration detecting device according to claim 6, wherein the substrate is made of a non-magnetic and conductive material. 8. The detecting member is formed of two permanent magnets (20, 21), whose magnetic polarities extend substantially parallel to each other and are oriented in the direction of the Hall element (30). And the polarity of the permanent magnets (20, 21) is
8. One of the claims 1 to 7, which is opposite to each other.
The acceleration detection device according to any one of the preceding claims. 9. The acceleration detecting device according to claim 1, wherein the casing (10) and the plug-in casing (12) are connected to each other by a snap connection member.